basically riot realized that the community is a bunch of babbies so they hid the elo (mmr same thing) so that you cannot see it, just like normals
then they slapped this new superficial system on top of it to make more people happy. Some people are still upset at some of the less thought out parts of the system (client crashing during a promo series loses you the whole thing) but for the most part people enjoy the whole "once you get gold/silver/plat/diamond so long as you keep playing ranked you won't drop"
LKS =/= MMR
LKS just uses your tier/division and reverse engineers it as best they can to represent what your elo in the old system would have been. It's just an estimation. --- ~GameFAQs LoL Board President~ http://i.imgur.com/6rO0g.png
Lolking score is basically the rating you would have if you were in the old system. --- Some people say I have no life. To those people: up up down down left right left right ;BA select start! Ding! 30 lives!!
And while I'm on the subject of MMR... How is it calculated? Is it like Elo rating? If so, what would be the point of the MMR?
Your LKS is not your MMR. The LKS is similar from the season 2 elo ratings but not the same. It follows the same convention. ie. Platinum V is 1850 LKS, Diamond V 2200 LKS etc.
elo ratings have been eliminated all together. If you are in your promotional series and have 100 LP(League points) you will notice that your LKS will not increase if you win and maintain 100LP. In season 2 your elo cannot remain static after a win or loss.
Your MMR is a hidden value that is based upon your wins and loses. Each game you will be match with a similar team's MMR. There is no way to see this value at the moment. If you are on a winning streak your MMR will keep increasing and you will play players well beyond your current ratings. You will gain more LP for a high MMR.
Ex. you are a bronze player and have high MMR. You will be playing against silver players. When you win the game you will get a higher than normal LP gain.